1. Field of the Invention
The present invention relates to a modularized power converter device wherein power semiconductors and control circuit devices are mounted on a circuit board, in particular, a power converter device to be installed in a vehicle.
2. Description of Related Art
These days, electric vehicles including hybrid cars come under the spotlight from the viewpoint of energy saving and prevention of air pollution. An alternating current electric motor, such as an induction motor, a synchronous motor, etc., is mainly adopted for a driving motor. Therefore, a power converter device called inverter, which converts direct current power that is supplied through a power battery into alternating current power, is necessary.
A hybrid car having such a power converter device will be described with reference to FIG. 14.
FIG. 14 shows a hybrid car 50, in which driving force by an alternating current dynamotor 35 is designed to be added to running driving force by an engine 30. The driving force by the engine 30 is transmitted from a transmission 31 to front wheels 33A and 33B through axles 32A and 32B; consequently, the front wheels 33A and 33B are rotary-driven, and the vehicle runs. The driving force by the alternating current dynamotor 35 is transmitted to a crankshaft of the engine 30, and added to the driving force by the engine 30.
This example describes a front-wheel drive vehicle, in which the front wheels 33A and 33B are driven by the engine 30. However, rear wheels may be configured to be driven by the engine. This system is also applicable to vehicles having six or more wheels such as a truck or tow vehicles such as a trailer.
The alternating current dynamotor 35, which is a motor generator (M/G), is, together with the engine 30, installed in an engine room, and connected to the crankshaft of the engine 30 using a belt 34. A power converter device 29 is connected to the alternating current dynamotor 35. Both a power battery 36 with voltage of, for example, 42V and a common in-vehicle battery 38 with voltage of 12V are connected to the power converter device 29.
The power battery 36 is a power supply for driving vehicles. The in-vehicle battery 38 is a power supply for driving accessories such as lights, air conditioners, etc. Hence, a winding field type three-phase alternating current electric rotating machine, for example, is used for the alternating current dynamotor 35. This enables electrical operation and electrical power generation at voltage of, for example, 42V, which is higher than that of a common in-vehicle battery.
The power converter device 29 works as a converter (power rectifier) when the alternating current dynamotor 35 is driven by the engine 30 and performs electrical power generation; while the power converter device 29 works as an inverter (reverse converter) when the alternating current dynamotor 35 works as a rotating electrical machine. When the power converter device 29 works as a converter, each battery is charged: the power battery 36 is provided with direct current power of 42V; while, the in-vehicle battery 38 is provided with direct current power of 12V. On the other hand, when the power converter device 29 works as an inverter, the direct current power of 42V, which is provided from the power battery 36, is converted into alternating current power with a predetermined voltage and a predetermined frequency, and is supplied to the alternating current dynamotor 35.
FIG. 15 shows an example of a circuit configuration of the power converter device 29. The power converter device 29 has a power module 290, which is connected to the power battery 36 or the in-vehicle battery 38 through a main circuit wiring 31. The power module 290, which is provided with semiconductor switching devices, performs switching operations by gate drive signal sent from a control circuit which is not figured herein. The power module 290 works as an inverter, that is, converting the direct current power supplied from the power battery 36 or the in-vehicle battery 38 into three-phase alternating current power with variable frequency, and supplying the current power to the alternating current dynamotor 35 through output wirings 32 of UVW phase.
When the alternating current dynamotor 35 performs the electrical power generation, the power converter device 29 works as a converter, which converts generated three-phase alternating current power into the direct current power, and charges the power battery 36 or the in-vehicle battery 38.
An electrolytic capacitor 20, which is connected to a direct current side of the power module 290, inhibits voltage variation of the direct current voltage caused by the switching operation of the semiconductor switching device of the power module 290.
The operation of the power converter device 29 is executed by a computerized control device which is not figured herein in accordance with a vehicle condition or a driver's operational state. As a result, the hybrid car 50 has a constant and precise running condition, an idling stop function, and a regenerative brake function, which lead to improvement of fuel consumption.
In accordance with this example, the motor generator 35 is connected to the engine 30 with the belt 34. However, other connecting means such as using a chain, etc. is applicable. The motor generator 35 may be configured between the engine 30 and the transmission 31, or may be configured in the transmission 31.
A heretofore known document which discloses such a hybrid car includes Japanese Laid Open Patent Publication No. 2002-136171 (patent document 1). A heretofore known document which discloses a power converter device includes U.S. Pat. No. 5,543,659 (patent document 2) and Japanese Laid Open Patent Publication No. 2006-165409 (patent document 3).
As described above, a power converter device, which is an important component of hybrid cars, etc., is supposed to supply electric power not only to a motor for driving but also to other electrical components such as an air conditioner. A recent increase in demand for vehicle's upgrade in performance and comfort brings about a steady increase in electrical energy in the in-vehicle power converter device.
Since vehicles are reduced in size and weight, a reduction of the power converter device, particularly that for in-vehicle purpose, in size and weight becomes an important issue. The in-vehicle power converter device, in comparison with that for industrial use, etc., is usually used in an environment with a significant temperature change; therefore, high reliability is required to be realized even in an extreme environment with as much power capacity and reduction in size and weight as possible.
In case of the vehicle, a lot of electronic devices (microcomputers) are usually used for engine control, vehicle running control, etc. Although these electronic devices are, in general, susceptible to electrical noise, they are supposed to be equipped inside the vehicle, which is a relatively small space, together with the power converter device. Consequently, in consideration of noise inhibition, the in-vehicle power converter device needs to be configured not to be a source of noise.
The present invention is to provide the power converter device which fulfills specifications for in-vehicle use.